Automatic Brightness Detection (ABD) is essential to an imaging detection, particularly to a real-time X-ray fluoroscopy. Automatic brightness detection comprises detecting the brightness of a given frame in a small region of interest (ROI), which is used to provide feedback to a system for automatic adjustment of imaging technical parameters (e.g., kV, mA . . . ). Existing methods for automatic brightness detection mainly rely on manual selection of a fixed ROI or simply move the ROI to a low grey-scale (thick anatomy) region. Such methods may give too low or too high signal in clinic practice, since the region of interest does not always remain constant in the view of a clinician, and is not always in the thickest anatomy.
Therefore, there is a need for method and apparatus for automatic brightness detection that can automatically detect a point of interest for a clinician, and then provide a more accurate feedback to an imaging system.